The use of legal and illegal psychoactive substances is an issue of major concern in our society. Although nicotine dependence, as well as concomitant use of nicotine and other drugs, is highly prevalent, particularly in treatment seeking substance abusers, the potential interactions of nicotine and other substances are not understood. This study is designed to examine the potential interactive effects of acute nicotine administration and chronic alcohol and/or stimulant abuse on brain electrophysiology in detoxified/abstinent substance abusers and community controls. Disentangling the interactive effects of these substances will lead to a better understanding of addictive processes and behavioral outcomes.